This invention relates to a surgical instrument for permanently closing vessels in a human or animal, and more particularly to a modified hemostat that fuses vessel tissue using a combination of pressure and electrosurgical current.
A hemostat is commonly used in surgical procedures to close off veins and arteries. It is typically a simple pliers-like tool that uses mechanical action between its jaws to constrict a vessel without cutting it. It is also typical to have an interlocking ratchet between the handles so that the device can be clamped and locked in place.
Many hemostats are used in a typical open surgical procedure. Once a structure has been clamped, it is common for a surgeon to tie a suture around the structure to close it off permanently prior to removing the hemostat. Several hemostats may be left in the surgical field until the surgeon has the opportunity to tie them all off. It would be desirable for surgeons the fuse the vessels immediately, and thus avoid having hemostats obstructing access to the surgical site.
A number of bipolar electrosurgical forceps and clamps are known in the field.
All of these designs suffer from the drawback that they do not combine the simplicity and familiarity of a hemostat with bipolar electrosurgery. For example, U.S. Pat. No. 5,462,546 discloses bipolar electrosurgical forceps comprising two interfacing pivotal blade members which are individually pivotable in relation to each other. Pivotal movement of the members is effectuated by two electrically conductive rigid rods extending through an elongated tubular member.
A U.S. Patent application entitled, Energy Delivery System for Vessel Sealing, Ser. No. 08/530,495, filed Sep. 19, 1995, discloses an apparatus and method for vessel sealing, and is hereby incorporated by reference and made a part of this disclosure.
A U.S. Patent application entitled, Vascular Tissue Sealing Pressure Control and Method, Ser. No. 08/530,450, filed Sep. 19, 1995, discloses a surgical tool for sealing vessels, and is hereby incorporated by reference and made a part of this disclosure.
U.S. Pat. No. 5,116,332 to Lottick discloses an electrocautery hemostat. The hemostat includes clam-shell type synthetic plastic handles with a switch incorporated therein.
U.S. Pat. No. 5,026,370 to Lottick discloses an electrocautery instrument with a non-removable enclosed electrical switching mechanism. U.S. Pat. No. 4,370,980 discloses an electrocautery instrument which may be used as a clamping device and an apparatus for cauterizing bleeding blood vessels during surgery.
U.S. Pat. No. 5,484,436 to Eggers discloses bipolar electrosurgical instruments. The bipolar instruments include opposite polarity electrodes isolated by a layer of electrical insulation deposited and specially prepared to reduce electrical breakdown and increase smoothness.
U.S. Pat. No. 5,443,464 to Stern et al. discloses a coagulating forceps having a plurality of electrodes and sensors on the jaws. The sensors provide a feedback signal to an electrosurgical generator in order to control the amount of heat in the forceps.
U.S. Pat. No. 4,005,714 to Hiltebrandt discloses bipolar coagulation forceps in which the forceps are designed to coagulate both the fallopian tube and the adjacent mesosalpinx.
It is the general objective of this invention to provide a instrument that can fuse structures without the need for a suture. The instrument has electrosurgical current flowing between the working jaws. The electrosurgical current passes through the clamped structure and forms a permanent seal.
One advantage of the invention is that blood vessels can be more quickly fused than with standard instruments.
Another advantage is that no sutures are required to permanently seal blood vessels.
Yet another advantage is that vessels can be sealed as the instrument is applied, and then the instrument can be removed from the surgical field. This keeps the surgical field clear of extraneous tools that may hinder the surgeon""s access to the surgical site.
The ability of the bipolar instrument to seal tissue partly depends on two elements: the pressure exerted on the vessel as it is grasped between the tissue contacting surfaces, and the characteristics of the bipolar electrosurgical energy which is conducted through the vessel. The pressure exerted on the vessel depends on the force exerted between the tissue contacting surfaces, and also on the cross sectional area of the tissue being grasped. It has been found through experimentation that a desirable force between the tissue contacting surfaces is less for ligating veins than for ligating arteries. It is desirable to avoid closure forces which cause the tissue to split or separate.
The characteristics of the bipolar electrosurgical energy are determined by the design of the electrosurgical generator. The bipolar instrument, described herein, is designed to be electrically connected to an electrosurgical generator with bipolar output.